Many software manufacturers equip their tools and applications with application programming interfaces (APIs). These make it possible to use certain functions of other programs or extend an application’s own range of functions. Functions like these can be misused in Outlook to spread malware. The malware variants include malicious tools and macros that directly exploit Outlook and its related e-mail features in order to obtain, change, or delete information. Macros can also be used to forward or relocate messages, dates, or tasks. Errors in macros may constitute an increased risk in this regard. Index errors in macros may produce incorrect results that cause an organisation to take poor business decisions. The specific consequences may include unnecessary costs or automated data leaks.